The invention involves a burner mechanism for a rotary kiln for the production of cement clinker from raw meal, with a burner lance movable in an axial direction, which extends through the stationary kiln outlet housing into the rotary kiln end.
At standard cement clinker production lines, calcined raw meal is burnt to cement clinker in the sintering zone of a rotary kiln by means of a burner lance extended through the kiln outlet housing creating a flame by means of fuel combustion. The red hot cement clinker is discharged through the kiln outlet housing onto a clinker cooler, in most cases grate coolers, and will be cooled down. In modern cement clinker production lines, the hot cooler air collected in the kiln outlet housing is utilized twofold. First, the hot air used as secondary air for the kiln firing and second, as tertiary air for a secondary firing system in the calciner stage installed according to the material flow upstream of the rotary kiln (brochure No. 7-330 KHD Humboldt Wedag AG, page 4 and 5).
The secondary air, which changes flow direction upon entering the kiln outlet end through the stationary kiln outlet housing from below, is loaded with cement clinker dust and has a high temperature of 1,100° C. and higher. Therefore the kiln outlet housing, and especially the burner lance, is exposed to a high mechanical abrasive and thermo/chemical wear. There are cases where the lifetime of a burner lance is extremely short, even if the burner lance is coated with heat resistance material and has a cooling system. An exchange or replacement of the burner lance requires interruption of the kiln operation and consequently an interruption of the whole cement clinker production line.